Small DNA Tumor Viruses have been shown to transform cells at least in part through the interaction of virally encoded oncoproteins with components of the cellular signal transduction and cell cycle machinery. Examples of such interactions include association of SV40 T ag, Ad E1A and HPV E7 with the retinoblastoma tumor susceptibility gene product, Rb, and the association of SV40 T ag, Ad E1b and HPV E6 oncoproteins with p53. Recent studies by Dr. Vande Pol and others have demonstrated that, unlike its relatives, the highly oncogenic human papillomaviruses associated with cervical cancer, bovine papillomavirus type 1 (BPV-1) encodes oncoproteins, E6 and E7, that do not interact with these cellular targets. Dr. Vande Pol argues that, through the study of these BPV-1 oncoproteins, novel cellular targets for virus-mediated transformation may be identified. The stated goals of Dr. Vande Pol's grant application are: 1) to elucidate the mechanism by which BPV-1 transforms cells, and 2) to identify the cellular targets of the BPV-1 E6 and E7 oncoproteins.